Dear respected DARLENE MULHALL,
Good morning! Thank you for posting in the Microsoft Community. We are happy to help you.
I'm sorry that you're having a problem, and from the situation you've encountered, we deeply understand the inconvenience caused and apologize for it.
According to your description, recently, we have received similar issues in this community. The class notebook tab removed/disappeared from the OneNote notebook online version of OneNote desktop client app.
Unfortunately, I have verified that there is currently no service incident. Since the issue happened to multiple users, I'm afraid this issue could be a temporary server-side issue that needs to be investigated through a remote section and collect logs and fixed on the backend.
I suggest you create a support ticket from the Microsoft 365 admin center and report the issue to the related team. The more reports they receive from different customers, the more likely they are to find something that affects mutual users, do an investigation, and fix it soon.
Reference: Get support - Microsoft 365 admin | Microsoft Learn
Note: To create a support ticket, you need to have Microsoft 365 admin privileges, and if you're not an admin for your Office 365 organization, contact the admin of creating a new ticket.
Reference: How do I find my Microsoft 365 admin? - Microsoft Support
Please accept my apologies and I'm sorry for not resolving the issue and redirecting it to the related development team, but the fix for your concern can be discovered through the HAR logs and suggest that you create a support ticket from the Office 365 admin center, where the related team will investigate the issue further by collecting the HAR logs.
We are redirecting you to the appropriate one to resolve the issue. That's why we suggest you contact your administrator or IT department. They can create a support ticket. Once your admin or IT contacts them, they will help you as soon as possible.
I'm sorry and I apologize for that.
Summary:
In the meantime, I would like to make a summary of this issue. This will also help other community members find a much easier solution if they find themselves in the same situation:
Description of the problem:
When users using Class Notebook through Class Teams. The option 'Class Notebook' has been removed(Class notebook tab disappeared) from the OneNote app9online version of OneNote desktop client app). This means Users cannot distribute page information from Notebook.
Environment:
Office 365 for business.
OneNote desktop client app.
OneNote web app.
Suggestion:
Since the issue happened to multiple users, I'm afraid this issue could be a temporary server-side issue that needs to be investigated through a remote section and collect logs and fixed on the backend.
I suggest you create a support ticket from the Microsoft 365 admin center and report the issue to the related team. The more reports they receive from different customers, the more likely they are to find something that affects mutual users, do an investigation, and fix it soon.
Reference: Get support - Microsoft 365 admin | Microsoft Learn
Note: To create a support ticket, you need to have Microsoft 365 admin privileges, and if you're not an admin for your Office 365 organization, contact the admin of creating a new ticket.
Reference: How do I find my Microsoft 365 admin? - Microsoft Support
Please accept my apologies and I'm sorry for not resolving the issue and redirecting it to the related development team, but the fix for your concern can be discovered through the HAR logs and suggest that you create a support ticket from the Office 365 admin center, where the related team will investigate the issue further by collecting the HAR logs.
We are redirecting you to the appropriate one to resolve the issue. That's why we suggest you contact your administrator or IT department. They can create a support ticket. Once your admin or IT contacts them, they will help you as soon as possible.
I appreciate your patience and understanding and thank you for your time and cooperation.
Sincerely
Waqas Muhammad